Musnad Abu Ya'la al-Mawsili 15:1

'Abd al-Rahman ibn Salih narrated to us, Yahya ibn 'Amr ibn Yahya ibn 'Amr ibn Salamah al-Hamdani narrated to me, from his father, from his grandfather, from his father, that the Messenger of Allah (peace and blessings of Allah be upon him) wrote to Qays ibn Malik al-Arhabi: "In Your name, O Allah. From Muhammad, the Messenger of Allah, to Qays ibn Malik. Peace be upon you, and the mercy of Allah, and His blessings, and His forgiveness. To proceed: I have appointed you over your people, their Arabs, their 'khumur' (villagers), their clients, and their retinue. And I have granted you from the corn of Yasar two hundred sa's, and from the raisins of Khaywan two hundred sa's. That shall be for you and your descendants after you, forever and ever." Qays said: "And the saying of the Messenger of Allah (peace and blessings of Allah be upon him), 'forever and ever,' is more beloved to me; I hope that my descendants will remain forever." Yahya said: "Their 'Arab' are the people of the desert, and their 'khumur' are the people of the villages."